Power amplification module

ABSTRACT

Provided is a power amplification module that supports a plurality of communication systems. The power amplification module includes: two power amplifiers that can be selectively connected in parallel with each other; a switch that, in accordance with one communication system selected from among the plurality of communication systems, selects one power amplifier that is to operate by itself from among the two power amplifiers or selects the two power amplifiers and connects the two power amplifiers in parallel with each other; and a phase correction circuit that, when the two power amplifiers are both selected, corrects a phase difference by being selectively connected between the outputs of the two selected power amplifiers such that a phase difference is not generated between the output signals of the two selected power amplifiers.

This is a continuation of U.S. patent application Ser. No. 15/709,787filed on Sep. 20, 2017, which claims priority from Japanese PatentApplication No. 2016-184165 filed on Sep. 21, 2016. The contents of eachof these applications is incorporated herein by reference in itsentirety.

BACKGROUND

The present disclosure relates to a power amplification module. There isa demand for mobile communication terminals such as cellular phones tobe able to support a plurality of communication systems (multi-mode) anda plurality of frequency bands (multi-band) as a single terminal.Examples of such communication systems include the global system formobile communications (GSM) (registered trademark), enhanced data ratesfor GSM evolution (EDGE), universal mobile telecommunications system(UMTS), wideband code division multiple access (W-CDMA), and long termevolution (LTE). The frequency bands are defined by telecommunicationsstandards in the respective communication systems. For example, only a 2GHz band was initially used as a frequency band in the third generationmobile communication system, but an 800 MHz band and a 1.7 GHz band werelater added due to the rapid increase in the number of users. Takingconvenience when overseas into consideration, it is desirable for mobilecommunication terminals to support an even greater number ofcommunication systems and frequency bands. In light of thesecircumstances, a power amplification module for use in a multi-modemulti-band mobile communication terminal is proposed in JapaneseUnexamined Patent Application Publication No. 2015-156687. The poweramplification module includes a plurality of power amplifiers and aplurality of switches used to select a combination of power amplifiersthat will operate in parallel in accordance with one communicationsystem selected from among a plurality of communication systems and inaccordance with the transmission power.

However, when a plurality of power amplifiers are made to operate bybeing connected in parallel with each other, a phase difference (phaseadvancement or phase retardation) may be generated between outputsignals of the plurality of power amplifiers due to externalenvironmental factors such as variations between circuits operating inparallel, temperature changes, load variations and so on, andconsequently oscillations may occur.

BRIEF SUMMARY

Accordingly, the present disclosure suppresses oscillations caused by aphase difference between output signals of power amplifiers operating inparallel.

A power amplification module according to an embodiment of the presentdisclosure supports a plurality of communication systems. The poweramplification module includes: (i) two power amplifiers that can beselectively connected in parallel with each other; (ii) a switch that,in accordance with one communication system selected from among theplurality of communication systems, selects one power amplifier that isto operate by itself from among the two power amplifiers or selects thetwo power amplifiers and connects the two power amplifiers in parallelwith each other; and (iii) a phase correction circuit that, when the twopower amplifiers are selected, corrects a phase difference by beingselectively connected between outputs of the two selected poweramplifiers such that a phase difference is not generated between outputsignals of the two selected power amplifiers.

According to the embodiment of the present disclosure, oscillationscaused by a phase difference between output signals of power amplifiersthat operating in parallel with each other can be suppressed.

Other features, elements, characteristics and advantages of the presentdisclosure will become more apparent from the following detaileddescription of embodiments of the present disclosure with reference tothe attached drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an explanatory diagram illustrating the fundamental circuitconfiguration of a communication module according to embodiment 1 of thepresent disclosure;

FIG. 2 is an explanatory diagram illustrating the fundamental circuitconfiguration of a communication module according to embodiment 2 of thepresent disclosure;

FIG. 3 is an explanatory diagram illustrating the fundamental circuitconfiguration of a communication module according to embodiment 3 of thepresent disclosure; and

FIG. 4 is an explanatory diagram illustrating the fundamental circuitconfiguration of a communication module according to embodiment 4 of thepresent disclosure.

DETAILED DESCRIPTION

Hereafter, embodiments of the present disclosure will be described whilereferring the drawings. Here, circuit elements that are the same as eachother will be denoted by the same symbols and repeated descriptionthereof is omitted. FIG. 1 is an explanatory diagram illustrating thefundamental circuit configuration of a communication module 100according to embodiment 1 of the present disclosure. The communicationmodule 100 is a module that is included in a mobile communicationterminal such as a cellular phone. The communication module 100 is fortransmitting and receiving radio frequency (RF) signals to and from abase station, and supports multiple modes and multiple bands. Here, acase will be exemplified in which the communication module 100 supportsGSM (registered trademark), EDGE and LTE, but the communication systemssupported by the communication module 100 are not especially limited. Inaddition, for convenience of explanation, circuit elements related toprocessing of a transmission signal are mainly illustrated, andillustration of circuit elements related to a reception signal isomitted.

The communication module 100 includes a baseband integrated circuit (IC)10, a radio frequency integrated circuit (RFIC) 20, a poweramplification module 31, a harmonic filter 41, duplexers 42 and 43, anantenna switch 50, an antenna 60, and a control circuit 70. The controlcircuit 70 may be built into the inside of the power amplificationmodule 31 or the inside of a chip.

The baseband IC 10 generates baseband signals for the respectivecommunication systems by performing digital signal processing. The RFIC20 generates a transmission signal by modulating a carrier wave inaccordance with information superposed on a baseband signal. Thetransmission signal is an RF signal that has a different frequency banddepending on the communication system used.

The power amplification module 31 is a module for amplifying the powerof a transmission signal. The power amplification module 31 includespower amplifiers AMP1, AMP2 and AMP3, a phase correction circuit PC1, amatching network MN1, a switch SW20 (first switch) and a switch SW1(second switch). The power amplifier AMP1 functions as a driver-stagepower amplifier that is connected upstream of the two power amplifiersAMP2 and AMP3. The two power amplifiers AMP2 and AMP3 function asoutput-stage power amplifiers. The outputs of the two power amplifiersAMP2 and AMP3 can be selectively connected in parallel with each othervia the phase correction circuit PC1 through an opening/closingoperation of the switch SW1. The phase correction circuit PC1 has acircuit configuration in which a resistor element and a capacitorelement are connected in parallel with each other, for example. Theswitch SW1 selectively connects the phase correction circuit PC1 betweenthe outputs of the two selected power amplifiers AMP2 and AMP3.

The control circuit 70 receives mode information indicating onecommunication system selected from among the plurality of communicationsystems from the baseband IC 10 or the RFIC 20. The control circuit 70outputs a control signal to the switch SW20 in response to the receivedmode information. The control signal instructs the switch SW20 to selectone power amplifier that is to operate by itself from among the twopower amplifiers AMP2 and AMP3 and connect the one power amplifier to apredetermined connection target. Alternatively, the control signalinstructs the switch SW20 to select the two power amplifiers AMP2 andAMP3 and commonly connect the two power amplifiers AMP2 and AMP3 to apredetermined connection target. Here, “predetermined connection target”refers to any one of the harmonic filter 41, the duplexer 42 and theduplexer 43 stipulated in the respective communication systems. Theswitch SW20 selects one power amplifier that is to operate by itselffrom among the two power amplifiers AMP2 and AMP3 and connects theselected power amplifier to the predetermined connection target inresponse to the control signal from the control circuit 70.Alternatively, the switch SW20 selects the two power amplifiers AMP2 andAMP3 and commonly connects the two power amplifiers AMP2 and AMP3 to thepredetermined connection target in response to the control signal fromthe control circuit 70.

The control circuit 70 outputs a control signal to the switch SW1 thatinstructs the switch SW1 to close when the control circuit 70 makes thetwo power amplifiers AMP2 and AMP3 operate in parallel with each other.The switch SW1 connects the phase correction circuit PC1 between theoutputs of the two power amplifiers AMP2 and AMP3 by closing in responseto the control signal from the control circuit 70. The control circuit70 outputs a control signal to the switch SW1 that instructs the switchSW1 to open when control circuit 70 makes either one of the two poweramplifiers AMP2 and AMP3 operate by itself. The switch SW1 severs theconnection established via the phase correction circuit PC1 between theoutputs of the two power amplifiers AMP2 and AMP3 by opening in responseto the control signal from the control circuit 70.

Next, a specific operation will be described for the case where the modeinformation indicating the communication system of the transmissionsignal is GSM (registered trademark) or EDGE, for example, that is, thecase where the mode information indicates a communication system inwhich a high output is required. In this case, the control circuit 70outputs a control signal to the switch SW20 that instructs the switchSW20 to select and commonly connect the two power amplifiers AMP2 andAMP3 to the harmonic filter 41, which is stipulated in advance. Inaddition, the control circuit 70 outputs a control signal to the switchSW1 that instructs the switch SW1 to connect the phase correctioncircuit PC1 between the outputs of the two power amplifiers AMP2 andAMP3. Thus, in the GSM (registered trademark) or EDGE communicationsystem, a transmission signal from the RFIC 20 is amplified by the twoparallel-connected power amplifiers AMP2 and AMP3 in addition to thepower amplifier AMP1, and is then guided to the harmonic filter 41. Thetransmission signal is guided to the antenna 60 from the harmonic filter41 via the antenna switch 50, and is then transmitted from the antenna60. In this case, even when a phase difference is generated between theoutput signals of the two power amplifiers AMP2 and AMP3 due to factorssuch as changes in temperature and variations in load, the phasedifference is made to converge to zero by the phase correction circuitPC1, and therefore, oscillations can be suppressed.

Next, a specific operation will be described for the case in which themode information indicating the communication system of the transmissionsignal is LTE very low band, for example, that is, the case where themode information indicates a communication system that operatessufficiently at a lower output than GSM (registered trademark) or EDGE.The control circuit 70 outputs a control signal to the switch SW20 thatinstructs the switch SW20 to select the one power amplifier AMP2 fromamong the two power amplifiers AMP2 and AMP3 and connect the selectedone power amplifier AMP2 to the duplexer 42, which is stipulated inadvance. In addition, the control circuit 70 outputs a control signal tothe switch SW1 that instructs the switch SW1 to sever the connectionestablished between the outputs of the two power amplifiers AMP2 andAMP3 via the phase correction circuit PC1. Thus, in the LTEvery-low-band communication system, a transmission signal from the RFIC20 is amplified by the power amplifier AMP2 in addition to the poweramplifier AMP1, and is then guided to the duplexer 42. The transmissionsignal is guided to the antenna 60 from the duplexer 42 via the antennaswitch 50, and is then transmitted from the antenna 60. The very lowband is a 700 MHz band, for example.

Next, a specific operation will be described for the case in which themode information indicating the communication system of the transmissionsignal is LTE low band, for example, that is, the case where the modeinformation indicates a communication system that operates sufficientlyat a lower output than GSM (registered trademark) or EDGE. The controlcircuit 70 outputs a control signal to the switch SW20 that instructsthe switch SW20 to select the one power amplifier AMP3 from among thetwo power amplifiers AMP2 and AMP3 and connect the selected one poweramplifier AMP3 to the duplexer 43, which is stipulated in advance. Inaddition, the control circuit 70 outputs a control signal to the switchSW1 that instructs the switch SW1 to sever the connection establishedbetween the outputs of the two power amplifiers AMP2 and AMP3 via thephase correction circuit PC1. Thus, in the LTE low-band communicationsystem, a transmission signal from the RFIC 20 is amplified by the poweramplifier AMP3 in addition to the power amplifier AMP1, and is thenguided to the duplexer 43. The transmission signal is guided to theantenna 60 from the duplexer 43 via the antenna switch 50, and is thentransmitted from the antenna 60. The low band is an 800 MHz band or a900 MHz band, for example.

The circuits can be designed in advance such that the power amplifiersAMP2 and AMP3 are able to amplify a GSM (registered trademark) or EDGEtransmission signal under optimal conditions by operating in parallel.Furthermore, the circuits can be designed in advance such that the poweramplifiers AMP2 and AMP3 are each able to amplify an LTE very low bandor LTE low band transmission signal under optimal conditions byoperating by themselves. The characteristics of the power amplifiersAMP2 and AMP3 do not necessarily have to be the same. In addition,although GSM (registered trademark) and EDGE have been exemplified ascommunication systems that require high output, a carrier aggregationsystem such as HP-UE may instead be adopted as a communication systemthat requires high output, for example.

As described above, according to embodiment 1, in the case where the twopower amplifiers AMP2 and AMP3 are both selected, phase differencecorrection is performed by the phase correction circuit PC1 such that nophase difference is generated between the output signals of the twopower amplifiers AMP2 and AMP3. Thus, even when a phase difference isgenerated between the output signals of the two power amplifiers AMP2and AMP3 due to factors such as changes in temperature or variations inload, the phase difference is made to converge to zero by the phasecorrection circuit PC1, and therefore, oscillations can be suppressed.

FIG. 2 is an explanatory diagram illustrating the fundamental circuitconfiguration of a communication module 200 according to embodiment 2 ofthe present disclosure. Symbols that are the same as those in FIG. 1denote the same circuit elements as in FIG. 1, and therefore thedescription will focus on the differences between embodiments 1 and 2. Apower amplification module 32 of embodiment 2 differs from the poweramplification module 31 of embodiment 1 in that the power amplificationmodule 32 includes a plurality of matching networks MN5, MN6, MN7 andMN8. In addition, the power amplification module 32 may include aplurality of power amplifiers.

The communication module 200 includes a baseband IC 10, an RFIC 20, thepower amplification module 32, a harmonic filter 41, duplexers 42 and43, an antenna switch 50, an antenna 60, and a control circuit 70. Thepower amplification module 32 includes power amplifiers AMP2 and AMP3,phase correction circuits PC1 and PC2, matching networks MN5, MN6, MN7and MN8, a switch SW20 (first switch), a switch SW30 (first switch), aswitch SW1 (second switch), a switch SW2 (fourth switch), a switch SW5(third switch), a switch SW6 (third switch), a switch SW7 (third switch)and a switch SW8 (third switch).

The inputs of the two power amplifiers AMP2 and AMP3 can be selectivelyconnected in parallel with each other via the phase correction circuitPC2 through an opening/closing operation of the switch SW2. The phasecorrection circuit PC2 has a circuit configuration in which a resistorelement and a capacitor element are connected in parallel with eachother, for example. The switch SW2 selectively connects the phasecorrection circuit PC2 between the inputs of the two selected poweramplifiers AMP2 and AMP3.

The matching network MN5 performs input impedance matching for the poweramplifier AMP2 by being selectively connected to the input of the poweramplifier AMP2 through an opening/closing operation of the switch SW5.The matching network MN6 performs output impedance matching for thepower amplifier AMP2 by being selectively connected to the output of thepower amplifier AMP2 through an opening/closing operation of the switchSW6. The matching network MN7 performs input impedance matching for thepower amplifier AMP3 by being selectively connected to the input of thepower amplifier AMP3 through an opening/closing operation of the switchSW7. The matching network MN8 performs output impedance matching for thepower amplifier AMP3 by being selectively connected to the output of thepower amplifier AMP3 through an opening/closing operation of the switchSW8. The matching networks MN5, MN6, MN7 and MN8 are each formed of acapacitor element, an inductor element or a combination of capacitorelements and inductor elements.

Next, a specific operation will be described for the case where the modeinformation indicating the communication system of the transmissionsignal is GSM (registered trademark) or EDGE, for example, that is, thecase where the mode information indicates a communication system inwhich a high output is required. In this case, the control circuit 70outputs control signals to the switches SW20 and SW30 that instruct theswitches SW20 and SW30 to select and commonly connect the two poweramplifiers AMP2 and AMP3 to the harmonic filter 41, which is stipulatedin advance. In addition, the control circuit 70 outputs a control signalto the switch SW1 that instructs the switch SW1 to connect the phasecorrection circuit PC1 between the outputs of the two power amplifiersAMP2 and AMP3. In addition, the control circuit 70 outputs a controlsignal to the switch SW2 that instructs the switch SW2 to connect thephase correction circuit PC2 between the inputs of the two poweramplifiers AMP2 and AMP3. In addition, the control circuit 70 outputscontrol signals to the switches SW5, SW6, SW7 and SW8 that instruct theswitches SW5, SW6, SW7 and SW8 to close, for example. Thus, in the GSM(registered trademark) or EDGE communication system, a transmissionsignal from the RFIC 20 is amplified by the two parallel-connected poweramplifiers AMP2 and AMP3, and is then guided to the harmonic filter 41.Next, the transmission signal is guided to the antenna 60 from theharmonic filter 41 via the antenna switch 50, and is then transmittedfrom the antenna 60. At this time, even when a phase difference isgenerated between the output signals of the two power amplifiers AMP2and AMP3 due factors such as changes in temperature and variations inload, the phase difference is made to converge to zero by the phasecorrection circuits PC1 and PC2, and therefore, oscillations can besuppressed. In addition, input impedance matching and output impedancematching are performed for the two power amplifiers AMP2 and AMP3 by theplurality of matching networks MN5, MN6, MN7 and MN8, and thereforemismatching loss can be suppressed.

Next, a specific operation will be described for the case in which themode information indicating the communication system of the transmissionsignal is LTE very low band, for example, that is, the case where themode information indicates a communication system that operatessufficiently at a lower output than GSM (registered trademark) or EDGE.The control circuit 70 outputs control signals to the switches SW20 andSW30 that instruct the switches SW20 and SW30 to select one poweramplifier AMP2 from among the two power amplifiers AMP2 and AMP3 andconnect the one selected power amplifier AMP2 to the duplexer 42, whichis stipulated in advance. In addition, the control circuit 70 outputs acontrol signal to the switch SW1 that instructs the switch SW1 to severthe connection established between the outputs of the two poweramplifiers AMP2 and AMP3 via the phase correction circuit PC1.Similarly, the control circuit 70 outputs a control signal to the switchSW2 that instructs the switch SW2 to sever the connection establishedvia the phase correction circuit PC2 between the inputs of the two poweramplifiers AMP2 and AMP3. In addition, the control circuit 70 outputscontrol signals to the switches SW7 and SW8 that instruct the switchesSW7 and SW8 to open while outputting control signals to the switches SW5and SW6 that instruct the switches SW5 and SW6 to close, for example.Thus, in the LTE very low band communication system, a transmissionsignal from the RFIC 20 is amplified by the power amplifier AMP2 and isthen guided to the duplexer 42. Next, the transmission signal is guidedto the antenna 60 from the duplexer 42 via the antenna switch 50, and isthen transmitted from the antenna 60. At this time, input impedancematching and output impedance matching are performed for the poweramplifier AMP2 by the plurality of matching networks MN5 and MN6, andtherefore mismatching loss can be suppressed.

Next, a specific operation will be described for the case in which themode information indicating the communication system of the transmissionsignal is LTE low band, for example, that is, the case where the modeinformation indicates a communication system that operates sufficientlyat a lower output than GSM (registered trademark) or EDGE. The controlcircuit 70 outputs control signals to the switches SW20 and SW30 thatinstruct the switches SW20 and SW30 to select one power amplifier AMP3from among the two power amplifiers AMP2 and AMP3 and connect theselected one power amplifier AMP3 to the duplexer 43, which isstipulated in advance. In addition, the control circuit 70 outputs acontrol signal to the switch SW1 that instructs the switch SW1 to severthe connection established between the outputs of the two poweramplifiers AMP2 and AMP3 via the phase correction circuit PC1.Similarly, the control circuit 70 outputs a control signal to the switchSW2 that instructs the switch SW2 to sever the connection establishedvia the phase correction circuit PC2 between the inputs of the two poweramplifiers AMP2 and AMP3. In addition, the control circuit 70 outputscontrol signals to the switches SW5 and SW6 that instruct the switchesSW5 and SW6 to open while outputting control signals to the switches SW7and SW8 that instruct the switches SW7 and SW8 to close, for example.Thus, in the LTE low band communication system, a transmission signalfrom the RFIC 20 is amplified by the power amplifier AMP3, and is thenguided to the duplexer 43. Next, the transmission signal is guided tothe antenna 60 from the duplexer 43 via the antenna switch 50, and isthen transmitted from the antenna 60. At this time, input impedancematching and output impedance matching are performed for the poweramplifier AMP3 by the plurality of matching networks MN7 and MN8, andtherefore mismatching loss can be suppressed.

As described above, the power amplification module 32 of embodiment 2includes the switches SW5 and SW7 that respectively selectively connectthe matching networks MN5 and MN7 to the inputs of the one or twoselected power amplifiers AMP2 and AMP3. Similarly, the poweramplification module 32 includes the switches SW6 and SW8 thatrespectively selectively connect the matching networks MN6 and MN8 tothe outputs of the one or two selected power amplifiers AMP2 and AMP3.Thus, the combination of the open/closed states of the switches SW5,SW6, SW7 and SW8 can be selected (or changed) in accordance with thepower amplifiers that are selected. Thus, input impedance matching andoutput impedance matching are selectively performed for the inputs andoutputs of the one or two selected power amplifiers AMP2 and AMP3, andtherefore mismatching loss can be reduced.

FIG. 3 is an explanatory diagram illustrating the fundamental circuitconfiguration of a communication module 300 according to embodiment 3 ofthe present disclosure. Symbols that are the same as those in FIG. 1denote the same circuit elements as in FIG. 1, and therefore thedescription will focus on the differences between embodiments 1 and 3. Apower amplification module 33 of embodiment 3 differs from the poweramplification module 31 of embodiment 1 in that the power amplificationmodule 33 includes three power amplifiers AMP2, AMP3 and AMP4 that canbe selectively connected in parallel with each other.

The communication module 300 includes a baseband IC 10, an RFIC 20, thepower amplification module 33, a harmonic filter 41, duplexers 42 and43, an antenna switch 50, an antenna 60, and a control circuit 70. Thepower amplification module 33 includes power amplifiers AMP1, AMP2, AMP3and AMP4, phase correction circuits PC1 and PC3, a matching network MN1,a switch SW40 (first switch), a switch SW1 (second switch) and a switchSW3 (second switch).

The control circuit 70 outputs a control signal to the switch SW40 inaccordance with one communication system selected from among a pluralityof communication systems and in accordance with the transmission power.The control signal instructs the switch SW40 to select one poweramplifier that is to operate by itself from among the three poweramplifiers AMP2, AMP3 and AMP4 and to connect the selected one poweramplifier to a predetermined connection target. Alternatively, thecontrol signal instructs the switch SW40 to select two or more poweramplifiers that are to operate in parallel with each other from amongthe three power amplifiers AMP2, AMP3 and AMP4 and commonly connect theselected two or more power amplifiers to a predetermined connectiontarget. The switch SW40 selects the one power amplifier that is tooperate by itself from among the three power amplifiers AMP2, AMP3 andAMP4 and connects the selected power amplifier to the predeterminedconnection target in response to a control signal from the controlcircuit 70. Alternatively, the switch SW40 selects the two or more poweramplifiers that are to operate in parallel with each other from amongthe three power amplifiers AMP2, AMP3 and AMP4 and commonly connects theselected two or more power amplifiers to the predetermined connectiontarget in response to a control signal from the control circuit 70.Here, “predetermined connection target” refers to any one of theharmonic filter 41, the duplexer 42 and the duplexer 43 stipulated bythe respective communication systems and transmission outputs.

The control circuit 70 outputs control signals to the switches SW1 andSW3 that instruct the switches SW1 and SW3 to close when control circuit70 makes the three power amplifiers AMP2, AMP3 and AMP4 operate inparallel with each other. The switch SW1 connects the phase correctioncircuit PC1 between the outputs of the two power amplifiers AMP2 andAMP3 by closing in response to the control signal from the controlcircuit 70. The switch SW1 selectively connects the phase correctioncircuit PC1 between the outputs of the two selected power amplifiersAMP2 and AMP3. Similarly, the switch SW3 connects the phase correctioncircuit PC3 between the outputs of the two power amplifiers AMP3 andAMP4 by closing in response to the control signal from the controlcircuit 70. The switch SW3 selectively connects the phase correctioncircuit PC3 between the outputs of the two selected power amplifiersAMP3 and AMP4.

The control circuit 70 outputs a control signal to the switch SW1 thatinstructs the switch SW1 to close when control circuit 70 makes the twopower amplifiers AMP2 and AMP3 from among the three power amplifiersAMP2, AMP3 and AMP4 operate in parallel with each other. At this time,the control circuit 70 outputs a control signal to the switch SW3 thatinstructs the switch SW3 to open. The switch SW1 connects the phasecorrection circuit PC1 between the outputs of the two power amplifiersAMP2 and AMP3 by closing in response to the control signal from thecontrol circuit 70. Similarly, the switch SW3 severs the connectionestablished via the phase correction circuit PC3 between the outputs ofthe two power amplifiers AMP3 and AMP4 by opening in response to thecontrol signal from the control circuit 70.

The control circuit 70 outputs control signals to the switches SW1 andSW3 that instruct the switches SW1 and SW3 to open when the controlcircuit 70 makes any one of the three power amplifiers AMP2, AMP3 andAMP4 operate by itself. The switch SW1 severs the connection establishedvia the phase correction circuit PC1 between the outputs of the twopower amplifiers AMP2 and AMP3 by opening in response to the controlsignal from the control circuit 70. Similarly, the switch SW3 severs theconnection established via the phase correction circuit PC3 between theoutputs of the two power amplifiers AMP3 and AMP4 by opening in responseto the control signal from the control circuit 70.

Next, a specific operation will be described for the case where the modeinformation indicating the communication system of the transmissionsignal is GSM (registered trademark) or EDGE, for example, and in whichthe transmission output is equal to or higher than a prescribedthreshold. In this case, all three power amplifiers AMP2, AMP3 and AMP4are selected and connected to the harmonic filter 41 by the switch SW40in accordance with an instruction from the control circuit 70. Thus, atransmission signal from the RFIC 20 is amplified by the threeparallel-connected power amplifiers AMP2, AMP3 and AMP4 in addition tothe power amplifier AMP1, and is then guided to the harmonic filter 41.The transmission signal is guided to the antenna 60 from the harmonicfilter 41 via the antenna switch 50, and is then transmitted from theantenna 60. At this time, even when a phase difference is generatedbetween the output signals of the three power amplifiers AMP2, AMP3 andAMP4 due factors such as changes in temperature and variations in load,the phase difference is made to converge to zero by the phase correctioncircuits PC1 and PC3, and therefore oscillations can be suppressed.

Next, a specific operation will be described for the case where the modeinformation indicating the communication system of the transmissionsignal is GSM (registered trademark) or EDGE, for example, and in whichthe transmission output is less than the prescribed threshold. In thiscase, the two power amplifiers AMP2 and AMP3 are selected from among thethree power amplifiers AMP2, AMP3 and AMP4 and connected to the harmonicfilter 41 by the switch SW40 in accordance with an instruction from thecontrol circuit 70. Thus, a transmission signal from the RFIC 20 isamplified by the two parallel-connected power amplifiers AMP2 and AMP3in addition to the power amplifier AMP1, and is then guided to theharmonic filter 41. The transmission signal is guided to the antenna 60from the harmonic filter 41 via the antenna switch 50, and is thentransmitted from the antenna 60. At this time, even when a phasedifference is generated between the output signals of the two poweramplifiers AMP2 and AMP3 due to factors such as changes in temperatureand variations in load, the phase difference is made to converge to zeroby the phase correction circuit PC1, and therefore, oscillations can besuppressed.

Next, a specific operation will be described for the case in which themode information indicating the communication system of the transmissionsignal is LTE very low band, for example, that is, the case where themode information indicates a communication system that operatessufficiently at a lower output than GSM (registered trademark) or EDGE.In this case, the one power amplifier AMP3 is selected from among thethree power amplifiers AMP2, AMP3 and AMP4 and connected to the duplexer42 by the switch SW40 in accordance with an instruction from the controlcircuit 70. Thus, a transmission signal from the RFIC 20 is amplified bythe power amplifier AMP3 in addition to the power amplifier AMP1, and isthen guided to the duplexer 42. The transmission signal is guided to theantenna 60 from the duplexer 42 via the antenna switch 50, and is thentransmitted from the antenna 60.

Next, a specific operation will be described for the case in which themode information indicating the communication system of the transmissionsignal is LTE low band, for example, that is, the case where the modeinformation represents a communication system that operates sufficientlyat a lower output than GSM (registered trademark) or EDGE. In this case,the one power amplifier AMP4 is selected from among the three poweramplifiers AMP2, AMP3 and AMP4 and connected to the duplexer 43 by theswitch SW40 in accordance with an instruction from the control circuit70. Thus, a transmission signal from the RFIC 20 is amplified by thepower amplifier AMP4 in addition to the power amplifier AMP1, and isthen guided to the duplexer 43. The transmission signal is guided to theantenna 60 from the duplexer 43 via the antenna switch 50, and is thentransmitted from the antenna 60.

Although a case has been exemplified in the above description in whichthe power amplification module 33 includes three power amplifiers AMP2,AMP3 and AMP4, the number of power amplifiers that can be connected inparallel with each other may be N. For example, in the case where thepower amplification module 33 includes N power amplifiers that can beselectively connected in parallel with each other, it is sufficient thatan i-th phase correction circuit be provided that can be selectivelyconnected between the output of an i-th power amplifier and the outputof an (i+1)-th power amplifier. Here, N is an integer of 3 or higher,and i is an integer in the range of 1 to N−1. In addition, in the casewhere the power amplification module 33 includes N power amplifiers thatcan be selectively connected in parallel with each other, the poweramplification module 33 may include at least one switch (second switch)that selectively connects at least one phase correction circuit betweenthe outputs of two or more selected power amplifiers. Furthermore, onepower amplifier that will operate by itself or two or more poweramplifiers that will operate in parallel with each other may be selectedfrom among N power amplifiers in accordance with one communicationsystem selected from among a plurality of communication systems and thetransmission power. For example, the number of power amplifiers that areselected may be changed if the transmission power is different even ifthe communication system remains the same.

According to embodiment 3, one power amplifier that will operate byitself is selected from among three or more power amplifiers inaccordance with one communication system selected from among a pluralityof communication systems. Alternatively, two or more power amplifiersthat will operate in parallel with each other are selected. Thus, avariety of communication systems having different transmission powerscan be supported. In particular, since the power amplifiers are selectedin accordance with the communication system and the transmission power,the optimum combination of power amplifiers can be selected in caseswhere the transmission power is different even if the communicationsystem remains the same.

FIG. 4 is an explanatory diagram illustrating the fundamental circuitconfiguration of a communication module 400 according to embodiment 4 ofthe present disclosure. Symbols that are the same as those in FIG. 2denote the same circuit elements as in FIG. 2, and therefore thedescription will focus on the differences between embodiments 2 and 4. Apower amplification module 34 of embodiment 4 differs from the poweramplification module 32 of embodiment 2 in that the power amplificationmodule 34 includes a plurality of matching networks MN9 and MN10, and apower amplifier AMP4.

The communication module 400 includes a baseband IC 10, an RFIC 20, thepower amplification module 34, a harmonic filter 41, duplexers 42 and43, an antenna switch 50, an antenna 60, and a control circuit 70. Thepower amplification module 34 includes power amplifiers AMP2, AMP3 andAMP4, phase correction circuits PC1, PC2, PC3 and PC4, matching networksMN5, MN6, MN7, MN8, MN9 and MN10, a switch SW40 (first switch), a switchSW50 (first switch), a switch SW1 (second switch), a switch SW2 (fourthswitch), a switch SW3 (second switch), a switch SW4 (fourth switch), aswitch SW5 (third switch), a switch SW6 (third switch), a switch SW7(third switch), a switch SW8 (third switch), a switch SW9 (thirdswitch), and a switch SW10 (third switch).

The outputs of the two power amplifiers AMP3 and AMP4 can be selectivelyconnected in parallel with each other via the phase correction circuitPC3 through an opening/closing operation of the switch SW3. The inputsof the two power amplifiers AMP3 and AMP4 can be selectively connectedin parallel with each other via the phase correction circuit PC4 throughan opening/closing operation of the switch SW4. The switch SW4selectively connects the phase correction circuit PC4 between the inputsof the two selected power amplifiers AMP3 and AMP4. The phase correctioncircuits PC3 and PC4 each have a circuit configuration in which aresistor element and a capacitor element are connected in parallel witheach other, for example.

The matching network MN9 performs input impedance matching for the poweramplifier AMP4 by being selectively connected to the input of the poweramplifier AMP4 through an opening/closing operation of the switch SW9.The matching network MN10 performs output impedance matching for thepower amplifier AMP4 by being selectively connected to the output of thepower amplifier AMP4 through an opening/closing operation of the switchSW10. The matching networks MN9 and MN10 are each formed of a capacitorelement, an inductor element or a combination of capacitor elements andinductor elements.

Next, a specific operation will be described for the case where the modeinformation indicating the communication system of the transmissionsignal is GSM (registered trademark) or EDGE, for example, and in whichthe transmission output is equal to or higher than a prescribedthreshold. In this case, all three power amplifiers AMP2, AMP3 and AMP4are selected and connected to the harmonic filter 41 by the switchesSW40 and SW50 in accordance with an instruction from the control circuit70. In addition, the switches SW1, SW2, SW3, SW4, SW5, SW6, SW7, SW8,SW9 and SW10 are closed in accordance with an instruction from thecontrol circuit 70. Thus, a transmission signal from the RFIC 20 isamplified by the three parallel-connected power amplifiers AMP2, AMP3and AMP4, and is then guided to the harmonic filter 41. The transmissionsignal is guided to the antenna 60 from the harmonic filter 41 via theantenna switch 50, and is then transmitted from the antenna 60. At thistime, even if a phase difference is generated between the output signalsof the three power amplifiers AMP2, AMP3 and AMP4 due factors such aschanges in temperature and variations in load, the phase difference ismade to converge to zero by the phase correction circuits PC1, PC2, PC3and PC4, and therefore, oscillations can be suppressed. In addition,input impedance matching and output impedance matching are performed forthe power amplifiers AMP2, AMP3 and AMP4 by the plurality of matchingnetworks MN5, MN6, MN7, MN8, MN9 and MN10, and therefore mismatchingloss can be suppressed.

Next, a specific operation will be described for the case where the modeinformation indicating the communication system of the transmissionsignal is GSM (registered trademark) or EDGE, for example, and in whichthe transmission output is less than the prescribed threshold. In thiscase, the two power amplifiers AMP2 and AMP3 are selected from among thethree power amplifiers AMP2, AMP3 and AMP4 and connected to the harmonicfilter 41 by the switches SW40 and SW50 in accordance with aninstruction from the control circuit 70. In addition, the switches SW1,SW2, SW5, SW6, SW7 and SW8 are closed and the switches SW3, SW4, SW9 andSW10 are opened in accordance with an instruction from the controlcircuit 70. Thus, a transmission signal from the RFIC 20 is amplified bythe two parallel-connected power amplifiers AMP2 and AMP3, and is thenguided to the harmonic filter 41. The transmission signal is guided tothe antenna 60 from the harmonic filter 41 via the antenna switch 50,and is then transmitted from the antenna 60. At this time, even if aphase difference is generated between the output signals of the twopower amplifiers AMP2 and AMP3 due factors such as changes intemperature and variations in load, the phase difference is made toconverge to zero by the phase correction circuits PC1 and PC2, andtherefore, oscillations can be suppressed. In addition, input impedancematching and output impedance matching are performed for the poweramplifiers AMP2 and AMP3 by the plurality of matching networks MN5, MN6,MN7 and MN8, and therefore mismatching loss can be suppressed.

Next, a specific operation will be described for the case where the modeinformation indicating the communication system of the transmissionsignal is LTE very low band, for example. In this case, the one poweramplifier AMP3 is selected from among the three power amplifiers AMP2,AMP3 and AMP4 and connected to the duplexer 42 by the switches SW40 andSW50 in accordance with an instruction from the control circuit 70. Inaddition, the switches SW7 and SW8 are closed, whereas the switches SW1,SW2, SW3, SW4, SW5, SW6, SW9 and SW10 are opened in accordance with aninstruction from the control circuit 70. Thus, a transmission signalfrom the RFIC 20 is amplified by the power amplifier AMP3, and is thenguided to the duplexer 42. The transmission signal is guided to theantenna 60 from the duplexer 42 via the antenna switch 50, and is thentransmitted from the antenna 60. At this time, input impedance matchingand output impedance matching are performed for the power amplifier AMP3by the plurality of matching networks MN7 and MN8, and thereforemismatching loss can be suppressed.

Next, a specific operation will be described for the case where the modeinformation indicating the communication system of the transmissionsignal is LTE low band, for example. In this case, the one poweramplifier AMP4 is selected from among the three power amplifiers AMP2,AMP3 and AMP4 and connected to the duplexer 43 by the switches SW40 andSW50 in accordance with an instruction from the control circuit 70. Inaddition, the switches SW9 and SW10 are closed, whereas the switchesSW1, SW2, SW3, SW4, SW5, SW6, SW7 and SW8 are opened in accordance withan instruction from the control circuit 70. Thus, a transmission signalfrom the RFIC 20 is amplified by the power amplifier AMP4, and is thenguided to the duplexer 43. The transmission signal is guided to theantenna 60 from the duplexer 43 via the antenna switch 50, and is thentransmitted from the antenna 60. At this time, input impedance matchingand output impedance matching are performed for the power amplifier AMP4by the plurality of matching networks MN9 and MN10, and thereforemismatching loss can be suppressed.

Although a case has been exemplified in the above description in whichthe power amplification module 34 includes three power amplifiers AMP2,AMP3 and AMP4, the number of power amplifiers that can be connected inparallel may be N. In this case, it is sufficient to provide a pluralityof matching networks that are selectively connected to the inputs andoutputs of the N power amplifiers and perform input impedance matchingand output impedance matching. N is an integer of 3 or higher.

As described above, the power amplification module 34 of embodiment 4includes the switches SW5, SW7 and SW9 that respectively selectivelyconnect the matching networks MN5, MN7 and MN9 to the inputs of the 1 or2 or more selected power amplifiers AMP2, AMP3 and AMP4. Similarly, thepower amplification module 34 includes the switches SW6, SW8 and SW10that respectively selectively connect the matching networks MN6, MN8 andMN10 to the outputs of the 1 or 2 or more selected power amplifiersAMP2, AMP3 and AMP4. Thus, the combination of the open/closed states ofthe switches SW5, SW6, SW7, SW8, SW9 and SW10 can be selected (orchanged) in accordance with the power amplifiers that are to beselected. Thus, input impedance matching and output impedance matchingare selectively performed for the inputs and outputs of the 1 or 2 ormore selected power amplifiers AMP2, AMP3 and AMP4, and thereforemismatching loss can be reduced.

The purpose of the embodiments described above is to enable easyunderstanding of the present invention and the embodiments are not to beinterpreted as limiting the present invention. The present invention canbe changed or improved without departing from the gist of the inventionand equivalents to the present invention are also included in the scopeof the present invention. In other words, appropriate design changesmade to the embodiments by one skilled in the art are included in thescope of the present invention so long as the changes have thecharacteristics of the present invention. The elements included in theembodiments and the arrangements, materials, conditions, shapes, sizesand so forth of the elements are not limited to those exemplified in theembodiments and can be appropriately changed. For example, the meaningof “a circuit element A is connected to a circuit element B” is notlimited to only the case where the circuit element A is directlyconnected to the circuit element B, and also includes the case where asignal path can be selectively established between the circuit element Aand the circuit element B via a circuit element C (for example, a switchelement). Furthermore, positional relationships in terms of directionssuch as above, below, left and right are not limited to the depictedproportions unless otherwise stated. In addition, the elements includedin the embodiments can be combined as much as technically possible andsuch combined elements are also included in the scope of the presentinvention so long as the combined elements have the characteristics ofthe present invention. For example, the combination of opening/closingstates of the switches may be freely selected or changed in accordancewith the desired characteristics.

While embodiments of the invention have been described above, it is tobe understood that variations and modifications will be apparent tothose skilled in the art without departing from the scope and spirit ofthe invention. The scope of the invention, therefore, is to bedetermined solely by the following claims.

What is claimed is:
 1. A power amplification module that supports aplurality of communication systems, the power amplification modulecomprising: two power amplifiers, wherein, based on a communicationsystem selected from among the plurality of communication systems, oneof the two power amplifiers operates by itself, or the two poweramplifiers operate in parallel with each other; and a phase correctioncircuit that, when the two power amplifiers operate in parallel, isconnected between outputs of the two power amplifiers and is configuredto remove a phase difference between output signals of the two poweramplifiers.
 2. The power amplification module according to claim 1,further comprising: a plurality of matching networks that areselectively connected to inputs and the outputs of the two poweramplifiers and are configured to perform input impedance matching andoutput impedance matching.
 3. The power amplification module accordingto claim 1, further comprising: a switch that selectively connects thephase correction circuit between the outputs of the two poweramplifiers.
 4. The power amplification module according to claim 2,further comprising: a switch that selectively connects the phasecorrection circuit between the outputs of the two power amplifiers. 5.The power amplification module according to claim 1, further comprising:a second phase correction circuit that, when the two power amplifiersare connected in parallel, is connected between inputs of the two poweramplifiers and is configured to remove a phase difference between inputsignals of the two power amplifiers.
 6. The power amplification moduleaccording to claim 1, wherein the phase correction circuit comprises aresistor and a capacitor connected in parallel.
 7. A power amplificationmodule that supports a plurality of communication systems, the poweramplification module comprising: at least three power amplifiers,wherein, based on a communication system selected from among theplurality of communication systems, only one of the at least three poweramplifiers operates by itself, or at least two of the at least threepower amplifiers operate in parallel with each other; and at least oneoutput phase correction circuit that, when the at least two poweramplifiers are connected in parallel, is connected between outputs oftwo of the at least two power amplifiers and is configured to remove aphase difference between output signals of the two of the at least twopower amplifiers.
 8. The power amplification module according to claim7, wherein the one of the at least three power amplifiers operates byitself based on the selected communication system and a transmissionpower corresponding to the selected communication system.
 9. The poweramplification module according to claim 7, further comprising: aplurality of matching networks that are connected to inputs and theoutputs of the at least two power amplifiers and are configured toperform input impedance matching and output impedance matching.
 10. Thepower amplification module according to claim 7, further comprising: oneor more switches that selectively connect the at least one output phasecorrection circuit between the outputs of the at least two poweramplifiers.
 11. The power amplification module according to claim 7,further comprising: at least one input phase correction circuit that,when the at least two power amplifiers are connected in parallel, isconnected between inputs of two of the at least two power amplifiers andis configured to remove a phase difference between input signals of thetwo of the at least two power amplifiers.
 12. The power amplificationmodule according to claim 7, wherein the at least one output phasecorrection circuit comprises a resistor and a capacitor connected inparallel.